Sound absorption device and method of manufacture



y 28, 1964 H. KAMMERER ETAL 3,142,354

SOUND ABSORPTION DEVICE AND METHOD 0F MANUFACTURE Filed y 28, 1961 I b \i \Q\) Te l:

INVENTORS #[ZMUT' KAM Fe/ '2 K/VAUE ATTORNEYS United States Patent F SOUND ABSORPTION DEVICE AND METHOD OF MANUFACTURE Hehnut Kammerer and Fritz Knauber, both of Oberhausen-Sterkrade, Germany, assignors to Gutehofinungshiitte Sterkrade Aktiengesellschaft, Oberhausen, Rhineland, Germany Fiied July 28, 1961, Ser. No. 127,600

Claims priority, application Germany Aug. 9, 1960 2 Claims. (Cl. 181-61) This invention relates in general to sound absorbers or silencers and methods of constructing such devices and in particular to a new and useful sound absorber and method of manufacturing same.

The sound absorber, according to the invention, includes a central assembly with a passage for the flow of fluid therethrough with outer compartmented areas surrounding the passage having sound absorbing material therein and an outer casing cast over the central assembly, in a manner to insure that the plates forming the partitioned areas of the central assembly extend into the outer casing.

The present sound absorber or silencer has particular application for arrangement in the inlet and discharge passages of large-sized air conmpressors. Such silencers have heretofore been constructed entirely by welding or by using mechanical connections between the various component parts. In such construction, the central assembly, which includes a tubular element through which the air is passed and a plurality of compartments, is formed by sheets or plates extending around the tubular element. Heretofore, the plates have either been secured by welding them to the tubular element or they were held in a spaced position along the length of the passage by means of bearing spacers and were connected together into an integral package or assembly at each end by the tie rods or tensioning rods. In both cases, however, in serts had to be built into the central assembly and the associated casing, before the casing could be connected to the pipe line at the inlets and outlets by means of connecting pieces. A disadvantage in such a construction is that the transverse sheets or plates which separate the sound absorbing material compartments cannot be easily sealed against the casing wall and against the central tubular or channel wall. Such imperfect sealing causes flow phenomena and pulsations between the spacers formed by the transverse sheets which lead to vibrations and shaking up and dislodgment of the sound absorbing material (for example, glass wool) which is .accomodated in the spaces. The sound absorbing material is thus torn apart and drawn into the central channel and blown away from the silencer. In addition, due to the strong pulsations, the weakly held transverse sheets may break during the flow of the air through the silencer and cause oscillation and complete breakage of the equipment.

In accordance with the present invention, there is provided a silencer which includes a central assembly or package comprising a central tubular element for the flow of the fluid therethrough and a plurality of compartment spacer plates surrounding the tube and disposed in axially spaced relationship therearound. The sound material compartment spacer plates are held in spaced relationship by an outer tubular element comprising the outer wall of the sound compartment. The spacer plates extend through the outer wall along an area extending over at least a portion of the periphery and end plates of greater thickness are welded to cover each end sound compartment to hold the assembly in place. In accordance with the invention, after the central assembly has been Patented July 28, 1964 completed and the compartments filled with sound absorbing material, an outer casing is cast integrally around the assembly and it includes side walls which are formed directly on the outer wall of the sound absorbing compartment and surrounding the peripheries of the spacer plates which extend into the passage. With such a construction, all the intermediate spaces of the spacer plates are completely sealed relative to each other and the overall structure is very strong and not subject to vibrations and loosening as in prior art structures.

Accordingly, it is an object of this invention to provide an improved sound absorbing device.

A further object of the invention is to provide a method of fabricating a sound absorbing device.

A further object of the invention is to provide a sound absorbing device, or silencer, which includes a central assembly with a central perforated tube for the flow of fluid therethrough and a plurality of sound absorbing material compartments defined along the length thereof by axially spaced spacer plates and a surrounding outer wall, and including an outer casing which is cast directly over the central assembly and extends between and around the outer peripheries of the spacer plates which extend sufliciently to become embedded in the casing.

A further object of the invention is to provide a silencer which is efiicient in operation, simple in design, rugged in construction and economical to manufacture.

The various features of novelty which characterize the invention are pointed out with particularity in the claims annexed to and forming a part of this specification. For a better understanding of the invention, its operating advantages and specific objects attained by its use, reference should be had to the accompanying drawings and descriptive matter in which there is illustrated and described a preferred embodiment of the invention.

In the drawings:

FIG. 1 is a transverse vertical section through an air compressor silencer constructed in accordance with the invention; and

FIG. 2 is an enlarged fragmentary horizontal section taken on the line 2-2 of FIG. 1.

Referring to the drawing in particular, the invention embodied therein includes a silencer having an outer casing 1 which includes a central cylindrical section a and end pieces b and 0. Each of the end pieces I) and c advantageously includes a flange portion 2 and 2' with an axially aligned opening 10 and 10 and a flange portion 3 and 3' with an opening 12 and 12' disposed at to the central axis of the device. The opening 10 is sealed by a plug 20.

In accordnace with the invention, the interior of the vessel includes a central assembly or package generally designated 14 around which the casing 1 is cast. The package 14 includes a central perforated pipe or tube 4 which is surrounded with a plurality of axially spaced spacers or plates 6. The extreme ends of the assembly are provided with plates 5 of relatively greater thickness than plates 6 and they are advantageously welded to the associated tube at each end. The end plates 5 and the plates 6 divide the space around the tube 4 into sections or compartments 7 which are filled with a suitable sound material, for example, glass wool 22.

After the spaces 7 are filled with sound absorbing matereduced diameters 6a at some circumferential locations in order to permit these portion to pass at the interior of the tubular element or pipe 8. It is essential, however, that at least portions 6b of the plates 6 extend beyond the outer face of the plate 8 through the slits therein. Thereafter, the casing 1 is .cast directly over the pipe 8 and the outer peripheries of the plates 6 extend into the casting, as indicated in the drawing.

As previously set forth, this construction of a silencer is very inexpensive to make and forms a very eflicient sound absorbing device which operates with a minimum amount of vibrations and with a surety that the portions will not become loose during operation.

While a specific embodiment of the invention has been shown and described in detail to illustrate the application of the inventive principles, it will be understood that the invention may be embodied otherwise without departing from such principles.

What is claimed is:

1. A sound absorption device comprising a central assembly including a perforated tubular member for the flow of fluid therethrough, a plurality of plates extending around said tubular member at axially spaced locations along the length thereof, an outer wall member extending between adjacent plates with the peripheries of at least a portion of said plates extending beyond the exterior face of said outer wall member, sound absorbing material disposed between said plates and said tubular member and said outer wall member, and an outer casing cast over said outer wall member with the outer peripheries of said plates extending into said casing casting.

2. A sound absorption device according to claim 1, wherein said casing casting includes openings at each end for the flow of fluid thereinto and thence through said tubular member.

References ilited in the file of this patent UNITED STATES PATENTS Re. 22,283 Bourne Mar. 9, 1943 788,242 Broga Apr. 25, 1905 973,756 Carter Oct. 25, 1910 1,693,317 Rice Nov. 27, 1928 2,514,996 Faust July 11, 1950 2,541,373 McLeod Feb. 13, 1951 FOREIGN PATENTS 25,729 Sweden Oct. 24, 1908 240,220 Great Britain Sept. 24, 1925 

1. A SOUND ABSORPTION DEVICE COMPRISING A CENTRAL ASSEMBLY INCLUDING A PERFORATED TUBULAR MEMBER FOR THE FLOW OF FLUID THERETHROUGH, A PLURALITY OF PLATES EXTENDING AROUND SAID TUBULAR MEMBER AT AXIALLY SPACED LOCATIONS ALONG THE LENGTH THEREOF, AN OUTER WALL MEMBER EXTENDING BETWEEN ADJACENT PLATES WITH THE PERIPHERIES OF AT LEAST A PORTION OF SAID PLATES EXTENDING BEYOND THE EXTERIOR FACE OF SAID OUTER WALL MEMBER, SOUND ABSORBING MATERIAL DISPOSED BETWEEN SAID PLATES AND SAID TUBULAR MEMBER AND SAID OUTER WALL MEMBER, AND AN OUTER CASING CAST OVER SAID OUTER WALL MEMBER WITH THE OUTER PERIPHERIES OF SAID PLATES EXTENDING INTO SAID CASING CASTING. 